In a liquid-vapor contacting column, intimate contacting of vapor and liquid flowing vertically in the column is sought by subdividing each phase to create a large exposed surface and contacting the subdivisions. A common technique is to pass the phases through a bed of packing seeking to cause the liquid to flow as films over the surfaces of the packing. Even with uniform distribution of the liquid across the column cross section at the top of the column, as the liquid descends, it agglomerates within the packing into rivulets that channel through the packing. The descending liquid also often flows preferentially along the column wall and agglomerates to flow as a film along the column wall. The agglomeration of the liquid reduces the desired interchange between the liquid and vapor, causing concentration gradients to occur in the liquid and vapor across the column cross section. To counter these effects, a vertical space is provided in the column for a device to mix the liquid and to mix the vapor and then distribute these mixed streams uniformly across the column cross section for further flow within the column in contact with each other.
There are known devices that cover the column cross section and allow vapor flows to pass through while collecting liquid from across the column cross section. These collectors then typically discharge the collected liquid downward through a downcomer pipe to a trough or pan occupying part of the cross section of the column. From the trough, the liquid is discharged further downward in a number of streams to a distributor plate or pan occupying substantially the full cross section of the column. The plate or pan has a number of distributed orifices for liquid flow and a number of distributed flues for vapor flow.
In such conventional devices, the distributor plate or pan is of thin gauge sheet metal. The orifices for liquid flow are formed by punching or drilling which leads to variation in size and shape of the orifices. The openings for installation of the flues are punched and the flues are welded into the openings. This punching and welding also distorts the plate or pan metal causing variations in the liquid orifices. During operation of the column, these variations in the liquid orifices cause variation in the magnitude of the liquid flows from the orifices and thus nonuniformity in the distribution of liquid across the column cross section.
In the known devices, the liquid flow or flows delivered to the distributor plate from above have considerable velocity and magnitude. Thus these flows spread laterally across the distributor plate with significant velocities. When a lateral flow occurs near a liquid orifice it alters the liquid head producing flow through the orifice. Consequently a variation in the magnitudes of flow delivered by the orifices occurs from this factor as well.
The known devices also require considerable column height which reduces the available height for packing and is costly to provide. The current invention alleviates the aforementioned shortcomings of the prior art.